The arguments against war are compelling: “America isn’t the world’s policeman.” “We’re tired of war.” “We don’t have the money.” Rep. Charlie Rangel (D-NY) cynically predicts that should we go to war, a Republican-dominated House will try to pay for it by cutting back programs for the poor and needy, rather than hiking taxes on the plutocrats who stand to benefit the most.

But there’s another argument we’re overlooking as we wallow in our isolationist self-interest. It’s about who we are as a nation. The Christian thinker St. Augustine, in his rationale for “just war,” listed certain conditions: All other avenues must be exhausted first. The ultimate objective must be peace. Most important is Augustine’s assertion that one commits a sin by standing back and doing nothing while helpless people are victimized.

We should at least pause to ponder the last condition, since we pride ourselves on being an exceptional nation. We may well decide that we want to turn our backs on the Syrian people, and in so doing, abandon our pretty myth of being the shining city on the hill. That is our prerogative.

Of course, there’s a counter-argument. We stood by while Saddam gassed his own people. We did nothing in Rwanda. There are many instances when America has let itself and the world down. To accept it, though, is to say that by our past failures, we have forever given up our identity as the nation that is motivated by what is right. We’ve already blown it, so why bother now?

As an ambivalent American, I’m looking for leadership, and I hope we’ll find some in President Obama’s speech on Tuesday. Obama has the luxury of not running for re-election, so his decisions about war may be relatively free of personal political considerations.

Obama has dropped hints that even if Congress fails to pass enabling legislation, he may decide to go it alone, in defiance of the American people and their duly elected representatives.

St. Augustine also said that a just war must be fought by the determination of an established government, not by individuals who harness a nation’s might to service their own ends.

In all this, I take the smallest bit of comfort: Whatever you may think of him, when it comes to grave decisions about war and humanity, Barack Obama is a better fit in the hot seat than Mr. “Corporations Are People Too, My Friend.”